The expressionS compact mass spectrometer (CMS) from Advion is a feature-packed high performance single quadrupole mass spectrometer. Some of the notable features of the expressionS CMS are: scanning speed, ease-of-use, in-source fragmentation and on-line polarity switching ability. This spectrometer is offered at nearly half the cost of other commercially available single quadrupole mass spectrometers, and its compact design makes it a perfect fit for laboratories facing space constraint. With these features, the CMS empowers more labs with the analytical advantages of mass spectrometry.
Significance of Analysis of Cannabis Sativa Plant
The active components of the cannabis sativa plant need to be analyzed for law enforcement to prevent illegal use of the material, and for control and optimization of the cannabis plant products in legal markets. Mass spectrometry is a preferred analysis tool for simple, reliable, and legally permitted detection and measurement of plant metabolites.
This article describes two simple analysis methods of cannabinoids, such as the psychoactive component of cannabis sativa, tetrahydrocannabinol (THC), naturally existing cannabinol (CBN), and the degradation product cannabidiol (CBD). Cannabinoids can be determined quantitatively using a combination of TLC/FIA/CMS, and THC can be nalyzed quantitatively using HPLC/CMS. Both methods highlight the advantage of using the CMS for natural product analysis.
Figure 1. A.) The expression CMS connected to the Plate Express, a device for the extraction of samples directly from a TLC plate. B.) A view of a developed TLC plate on the Plate Express platform.
Figure 2. Chemical structures of the three compounds studied
Thin Layer Chromatography (TLC)
The separation of cannabinoids was performed using TLC silica gel 60 F254 and a run solvent consisting of 80/20 Petrolether (60-80bp) / Dioxane.
TLC/FIA/MS analysis was performed with Advion’s Plate Express™ sample extraction device, using methanol with 0.1% volume formic acid at a flow rate of 200µL/min.
A 1220 HPLC system equipped with a UV detector was employed for sample analysis on a Supelco Titan 2.1mm column, using 50% to 90% acetonitrile with 0.1% volume formic acid at a flow rate of 350µL/min and a 5 minute gradient.
Both in-source CID and polarity switching were used to scan a mass range of m/z 100 to m/z 1000. Quantitative analysis was then performed using SIM scanning in the negative ion mode MS at m/z 313.2 (THC and CBD) and m/z 309.2 (CBN). The expressionS CMS mass spectrometer was used in these MS analysis methods.
The Plate Express sample extraction device analyzes a lane on a TLC plate either individually or sequentially, and performs sample extraction and transportation to the CMS for subsequent analysis, as shown in Figure 3.
Figure 3. TLC/FIA/CMS analysis of cannabinoids. 3a) A typical TLC separation of an analytical mixture of CBD, CBN and THC at 1μg material on the lane. TLC/FIA/CMS analysis of the Rf region of THC (Rf=0.47) shows a strong MS TIC signal (3b) with a prominent negative ion signal at m/z 313.2 (data not shown) and the characteristic in-source CID fragments of THC (3c). An alternative approach analyzing the whole TLC lane shows that CBN, CBD and THC are not baseline separated during TLC analysis (3d), so quantitative analysis should use HPLC/CMS.
Figure 3a illustrates the qualitative analysis of THC using TLC/FIA/MS. The resulting negative ion mode in-source CID MS is shown in Figure 3b, accurately determining the presence of THC in the sample. The positive ion mode MS that was simultaneously acquired and the corresponding in-source CID MS data are not shown here.
THC and CBD have a different molecular structure, but their isotopic mass is the same and their fragmentation is identical in positive ion mode ESI/MS data. However, in negative ion mode, THC and CBD can be discerned from the in-source CID data, which yields the same m/z fragments but their relative intensities differ significantly.
The quantitative analysis involved an HPLC/CMS setup to determine CBD, CBN and THC, using SIM scanning in negative ion mode and a separation time of 10 minutes (Figure 4a). Cannabinoid standards were analyzed three times, yielding calibration functions with a good linearity ranging from 2.5 to 250ng on column. This value is adequate to measure from cannabis plant materials, such as leaves, stems and roots, with only 0.1% w/w content.
Figure 4. A) A typical HPLC/CMS chromatogram for all three analytes in negative ion mode SRM with the upper trace being the XIC of m/z 313.2 and the lower trace XIC of m/z 309.2. Good linearity calibration functions can be obtained for all three compounds (B: THC, C: CBD and D: CBN) covering a range from 250 to 2.5ng analyte on the 2.1mm ID column used – sufficient to analyze plant material with as little as 0.1% w/w THC content.
High quality data is gained from natural products with the help of the expressionS CMS. This information is useful in law enforcement as well as in controlling the quality of legal cannabis sativa-based products.
A combined TLC/FIA/CMS technique allows for the targeted mass analysis directly from thin-layer chromatography (TLC) plates, thereby speeding up the analytical process as well as providing detailed information about an unknown substance. Further, an HPLC/CMS method can be employed to quantify CBN, THC and CBD in known products. The flexibility of the expression CMS is ideal at the center of a natural products laboratory.
About Advion, Inc.
Advion develops, manufactures and globally supports mass spectrometers, chip-based ion sources, microfluidic flow chemistry systems and consumables for life science and related industries. We seek to enhance analysis performance and workflows. Using our deep scientific and engineering knowledge of mass spectrometry and microfluidics, we leverage our passionate employees’ commitment to create quality, flexible and fit-for-purpose solutions. More about Advion, Inc. can be found on our website, www.advion.com.
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